In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure O=P(OR)₃, a central phosphate molecule with alkyl or aromatic substituents. They can be considered as esters of phosphoric acid.

Like most functional groups, organophosphates occur in a diverse range of forms, with important examples including key biomolecules such as DNA, RNA and ATP, as well as many insecticides, herbicides, nerve agents and flame retardants. OPEs have been widely used in various products as flame retardants, plasticizers, and performance additives to engine oil. The popularity of OPEs as flame retardants came as a substitution for the highly regulated brominated flame retardants. The low cost of production and compatibility to diverse polymers made OPEs to be widely used in industry including textile, furniture, electronics as plasticizers and flame retardants. These compounds are added to the final product physically rather than by chemical bond. Due to this, OPEs leak into the environment more readily through volatilization, leaching, and abrasion. OPEs have been detected in diverse environmental compartments such as air, dust, water, sediment, soil and biota samples at higher frequency and concentration.